The present invention relates to a device for opening and closing bottom outlets of a plurality of cargo pockets arranged in rows, preferably in holds in bulk cargo ships, conveyors being arranged beneath the pockets.
In so called self-unloading bulk cargo ships in which the bulk cargo is emptied down onto conveyor belts situated below the holds for further transport to conveyors leading out from the ship, the bottom portion of the holds is usually designed so that it forms a plurality of V-shaped pockets extending in both the fore-and-aft and thwartships directions. Each pocket has an outlet opening which enables 100% emptying of the holds without requiring any extra measures. In a known embodiment, the outlets are sealed by pivotably journalled tapping chutes or spouts operated by hydraulic cylinders which, in a raised position, seal the outlet of the pocket and which, in a lowered position, expose the outlet and lead the material down to the underlying conveyor belt. Beyond 100% emptying, the large number of load pockets which can be individually emptied makes it possible to keep the ship correctly trimmed during unloading.
However, one disadvantage of the described arrangement is that it is very expensive to install. As an example, it can be mentioned that bulk cargo ships of approx. 20,000 tdw can have up to 80 load pockets, each of which is provided with a tapping spout with accompanying hydraulic cylinders, conduits and valves. Due to this, service and maintanance work becomes demanding and costs are high. Another disadvantage is that the inverted V-shaped ridges running in the fore-and-aft and thwartships direction between the pockets must be relatively large in order to provide space for the underlying equipment. This results in that the cargo space is reduced.